Chronic High-Dose Buprenorphine Does Not Block Subjective High from Diacetylmorphine in a Patient in Heroin-Assisted Treatment.

We present the case of a 35-year-old woman in heroin-assisted treatment (HAT) expressing the wish for the transition to oral opioid agonist treatment. After failed attempts to change to oral diacetylmorphine and slow-release oral morphine, respectively, she was induced on overlapping buprenorphine (BUP) treatment with the Bernese method. Gradual dose increases to BUP 48 mg per day did not result in attenuation of subjective effects of IV diacetylmorphine (DAM) 190 mg. Instead, the patient showed increased sedation. BUP was then reduced to 32 mg per day. After the gradual reduction of IV DAM, she reinitiated illicit substance use. IV DAM was again raised to an effective dose leading to stabilization and reduction of illicit substance use. BUP was subsequently reduced to 8 mg per day. This combination was continued as the patient felt comfortable and reported less early morning withdrawal than with exclusive DAM treatment. We discuss possible underlying mechanisms and explanations as well as clinical implications.